1. Field of the Invention
This invention relates generally to back-check valves for permitting pressurized fluid flow in only one direction, and particularly for valves suitable for use in medical administration sets.
2. Description of the Prior Art
A common problem with known type check valves is the lack of sensitivity thereof. Also, often they fail to function properly and/or leak fluid therefrom during use.
Another common problem of known one-way valves is with the valve disc per se, that is, the disc does not fit properly, or a peripheral edge engages, binds, or sticks against an inner surface of the valve body.
A still further problem is that the known type valve discs leave much to be desired in flexibility and/or semi-rigidness. The materials generally used for such discs fail to meet all of the desired performance qualities, and still be relatively inexpensive.
Existing prior patents which may be pertinent to this invention are as follows:
______________________________________ 3,625,211 Butler 12/7/71 3,889,710 Brost 6/17/75 4,141,379 Manske 2/27/79 4,222,407 Ruschke, et al 9/16/80 4,354,492 McPhee 10/19/82 ______________________________________
The U.S. Pat. No. 3,625,211 to Butler, shows a medical administering set of the type with which the present invention is preferably used. However, the valve structure of this patent is entirely different from that of the present invention.
U.S. Pat. No. 3,889,710 to Brost, discloses a single disc element 13 which is shown in the closed position in FIG. 5 and in the open position in FIG. 6 of the drawings; however, in neither of these positions is the single disc mechanically biased against the valve seat. Also, there is nothing in this disclosure to teach the desirability of having a valve member of dual disc construction as in the present invention.
The Manske U.S. Pat. No. 4,141,379 discloses a flexible diaphragm 48 comprised of a screen 52, and in its center a resilient disc 54 which either rests loosely on screen 52 or is secured thereto by adhesive. While this structure is somewhat related to that of the present invention, neither the dual disc construction as disclosed herein, nor the positive mechanical biasing of the dual disc against the valve seat in normally closed position is taught by this patent.
The Ruschke, et al U.S. Pat. No. 4,222,407 discloses a single valve member which is biased against the valve seat by a rib 58 which extends traversely entirely across the valve body housing. Again, only a single valve member disc is disclosed, and the biasing arrangement is substantially different from that of the present invention.
U.S. Pat. No. 4,354,492 to McPhee, discloses a single flexible valve disc member which is not mechanically biased against the valve seat, but is free floating at all times within the valve housing. Also, a predetermined spacing distance between the valve disc member and the valve seat is also important in this device.
None of the known prior art devices offers the new and novel features of the present invention.